Conditions for the synthesis of the SnO₂-Au _x ⁰ -(H₃PW₁₂O₄₀) _y •nH₂O nanocomposite layers by the method of ionic epitaxy were determined for the first time. The layers we investigated by the method of scanning electron microscopy, energy dispersion microanalysis, UV and IR Fourier transmission spectroscopy. On the basis of the experimental data conclusions were drawn on the composition and structure of the synthesized layers.